What Is a Solar Eclipse?
The Sun is about 400 times wider than the Moon—and about 400 times farther away. That remarkable coincidence makes them appear almost the same size in our sky. When the Moon passes between Earth and the Sun at the right alignment, it hides part or all of the Sun's bright face and casts a shadow on Earth.
What is moving?
The Moon orbits Earth. Earth rotates and travels around the Sun. During an eclipse, those motions combine to carry the Moon's shadow across Earth's daylight side. The dark central shadow is the umbra; observers inside it can see totality. The wider penumbra produces a partial eclipse.
Three kinds of solar eclipse
Total
Inside the narrow path of totality, the Moon completely covers the bright solar surface. The sky becomes twilight-like and the faint solar corona appears. Glasses stay on before and after totality and may come off only during complete totality.
Partial
The Moon covers only part of the Sun. There is no safe glasses-off phase; proper solar protection is required whenever looking directly at it.
Annular
The Moon appears slightly too small to cover the Sun, leaving a bright ring. The ring is direct sunlight, so protection remains on throughout.
Why not every month?
The Moon's orbit is tilted by about five degrees relative to Earth's orbital plane. Most new Moons pass above or below the Sun. An eclipse occurs only near the crossing points of those planes.
Why is 99% not totality?
Even a narrow uncovered sliver of Sun remains overwhelmingly bright. At 99%, glasses stay on. At verified 100% totality inside the path, they may come off briefly. One percentage point creates a different view and a different safety rule.
Spain 2026
On 12 August 2026, totality crosses northern Russia, Greenland, Iceland, the Atlantic and Spain. Much of northern Spain sees totality close to sunset; southern Spain sees a deep partial eclipse. Explore locations and timings in our Spain 2026 guide.
Before observing, read How to Use Eclipse Glasses and check our compliance documents.